1. Field of the Invention
The present invention relates to a switch such as a seesaw type switch, a lever switch or the like used in a power window switch or the like of an automobile.
2. Description of the Related Art
There is a conventional seesaw type switch as shown by FIG. 12 and FIG. 13 described in, for example, Japanese Utility Model Laid-Open No.20844/1991. FIG. 12 is a disassembled perspective view and FIG. 13 is a sectional view.
As shown by FIG. 12 and FIG. 13, a conventional seesaw type switch 201 is provided with fixed terminals 205 and 207 and a common fixed terminal 209 at a terminal board 203. A movable contact piece 211 is pivotably supported by the common fixed terminal 209. Movable contacts 213 and 215 are provided at both ends of the movable contact piece 211. The movable contact piece 211 is formed by a plate member and is arranged such that a plate face thereof is directed upwardly. A pin 217 is brought into elastic contact with an upper face of the movable contact piece 211. The pin 217 is contained in a sliding member 219 via a coil spring 221.
Therefore, when the sliding member 219 is moved to a state of FIG. 13 by operating the switch knob, the movable contact 213 on one side is brought into contact with the fixed contact 205 on one side and the fixed contact 205 on one side and the common fixed contact 209 are conducted to each other. Further, when the sliding member 219 is moved to the right side of FIG. 13 by operating the switch knob, the pin 217 is moved to the right side of the common fixed contact 209 by smoothly sliding on the upper face of the movable contact piece 211 by the elastic contact. By moving the pin 217, the movable contact piece 211 is rotated in the clockwise direction in FIG. 13 and the movable contact 215 on other side is brought into contact with the fixed contact 207 on other side. Thereby, the fixed contact 207 on other side and the common fixed contact 209 are conducted to each other.
In this way, by operating the movable contact piece 211 in seesaw movement by operating the switch knob, the movable contacts 213 and 215 can be brought into contact with and separated from the fixed contacts 205 and 207.
Meanwhile, according to the power window switch of an automobile, a click feeling is given to operation of the switch knob in order to give an operator differentiation among lifted and lowered positions and a neutral position of switch operation as the operation feeling.
However, according to the above-described structure, excellent click feeling cannot be given by a side of the movable contact piece 211 and therefore, there must be provided separately a portion having a click groove, a steel ball which is brought into elastic contact with the click groove and a coil spring for urging the steel ball between the switch knob and a switch case. Therefore, there are needed the steel ball and the coil spring other than the pin 217 and the coil spring 221, a number of parts is large, assembling and parts control is complicated to thereby cause an increase in cost.
Further, conventionally, according to a click member of a seesaw type switch, there is used the pin 217 which is long in an up and down direction such that the pin 217 is not detached from the sliding member 219 even when the pin 217 is slided on the movable contact piece 211. The pin 217 is used when an amount of sliding the pin 217 on the movable contact piece 211 is large and a steel ball cannot be used since the steel ball is detached from the sliding member 219. A front end of the pin 217 is constituted by a spherical shape and therefore, it is difficult to fabricate the pin 217 by a large amount when the pin 217 is made of a metal and therefore, a pin molded by resin is generally used. However, there poses a problem that the pin 217 made of resin is devoid of durability and expensive in comparison with the steel ball.
With regard thereto, the present assignee has already proposed a structure as described in Japanese Utility Model Laid-Open No.145232/1988. According to the structure, a movable contact piece is bent by pressing to thereby form a click ridge and a steel ball supported by a slider is brought into contact with the movable contact piece by urge force of a coil spring. Further, a click feeling can be given to a switch knob by cooperatively moving the slider by operating a switch knob and making the steel ball ride over the click ridge.
However, there poses a problem that in forming the click ridge by pressing the movable contact piece, it is difficult to accurately form the click ridge by springback of the movable contact piece in pressing and the degree of freedom of setting a height and a shape of the click ridge is narrow. Further, due to sliding between the movable contact piece made of a metal and the steel ball made of a metal, abrasion powder is produced and a contact failure is caused and in order to achieve smooth sliding, it is necessary to significantly improve an accuracy of finishing a surface of the movable contact piece to thereby cause an increase in cost.
Further, a movable contact board on which the steel ball slides, must be formed such that the ridge portion is lowered and the valley portion is shallowed to prevent the steel ball from being detached from a holder and a change in operational force (click feeling) is reduced when the knob is pivoted. Therefore, according to the seesaw type switch using the steel ball, there poses a problem in which operation feeling is poor and erroneous operation is liable to be brought about since the position is changed from an OFF position to ON position by small operational force.
It is an object of the invention to provide a switch such as a seesaw type switch, a lever switch or the like capable of widening the degree of freedom of setting a height and shape of a click groove while providing the click groove on the side of a movable contact and capable of promoting an operation feeling without increasing cost thereof.
According to a first aspect of the invention, the invention is concerned switch comprising a fixed contact fixedly supported by a housing, a movable piece pivotably supported by the housing and having a movable contact brought into contact with and separated from a fixed contact, and a switch knob pivotably supported by the housing for operating to move an elastic contact member brought into elastic contact with the movable piece, wherein the movable contact is brought into contact with and separated from the fixed contact by pivoting the movable piece by moving the elastic contact member on the movable piece by operating to pivot the switch knob, and wherein the movable piece is provided with a contact portion made of a conductive material and a click portion made of a resin having a click groove.
According to a second aspect of the invention, in the switch according to the first aspect, the click portion of the movable piece is formed to be flat and comprise the click groove at an end edge thereof and the click portion of the movable piece is arranged to erect relative to the housing such that the elastic contact member is brought into elastic contact with the click groove, wherein the elastic contact member is formed by a steel ball, further comprising a ball support portion in a cylindrical shape for containing the steel ball via an urging member and having an opening at an end portion thereof wherein the opening of the ball support portion is provided with an engaging groove loosely fitted to the end edge of the click portion of the movable piece.
According to a third aspect of the invention, in the switch according to the first or second aspect, a section of the click groove is formed in a recessed shape in accordance with an outer face in a spherical shape of the steel ball.
According to a fourth aspect of the invention, in the switch according to any one of the first to third aspects, the switch further comprises a containing wall portion provided at the housing for surrounding the fixed contact, a slider supporting the elastic contact member and moved by operating to pivot the switch knob, and a slider cover attached to the containing wall portion attachably and detachably, forming a containing space for containing the slider and the movable piece between the slider cover and the containing wall portion and covering the slider movably.
According to the invention of the first aspect, the elastic member which is brought into elastic contact with the movable piece can be operated to move by the switch knob pivotably supported by the housing. The movable piece is pivotably supported by the housing and when the elastic contact member is moved on the movable piece, the movable piece is pivoted and the movable piece can be brought into contact with and separated from the fixed contact fixedly supported by the housing.
Further, the movable pieces provided with the contact portion made of the conductive material and the click portion made of the resin having the click groove and therefore, the click groove can easily be formed at the click portion on the side of the movable contact. Further, the click groove is provided at the click portion made the resin and therefore, a degree of freedom of setting height and shape of the click groove can significantly be widened. The click groove is provided at the click portion made of the resin and therefore, contact of the elastic contact member can smoothly be carried out without providing special surface finish and promotion of operation feeling of the switch knob can be achieved without increasing cost.
According to the invention of the second aspect, in addition to the effect of the invention of the first aspect, the click portion of the movable piece is formed to be flat and is provided with the click groove at the end edge and the click portion of the movable piece is arranged to erect relative to the housing such that the elastic contact member is brought into elastic contact with the click groove, the elastic member is formed by the steel ball, there is further provided the ball support portion in the cylindrical shape for containing the steel ball via the urging member and having the opening at the end portion, the opening portion of the ball support portion is provided with the fitting groove for loosely fitting to the end edge of the click portion of the movable piece and therefore, opening of the ball support portion can be closed by the end edge of the movable piece. Therefore, when the steel ball is moved on the movable piece, the steel ball can be restrained from being detached from the ball support portion and fall of the movable piece can be restrained. In this way, pivoting movement of the movable piece can firmly be carried out, contact and detachment of the movable contact to and from the fixed contact can further firmly be carried out and space can be saved by narrowing a lateral width of the click groove and downsizing of the switch can be achieved.
Further, the flat click portion of the movable piece is arranged to erect relative to the housing and therefore, the degree of freedom of setting height of the click groove can firmly be widened.
Further, since the steel ball is formed by a spherical shape, friction coefficient is small, the steel ball is inexpensive, hard and excellent in durability in comparison with a click pin made of a resin, easy to fabricate and inexpensive owing to a standard product also in comparison with a click pin made of a metal. The click portion of the movable piece to which the fitting groove of the ball support portion is fitted, is made of resin, the smooth face can be formed without finishing the surface, movement between the ball support portion and the movable piece can be made smooth, abrasion powder is prevented from being brought about since metals are not brought into contact with each other, durability of the movable piece having the click groove can be promoted and operation feeling of the switch knob can be promoted.
According to the invention of the third aspect, in addition to the invention of the first or second aspect, the section of the click groove is formed in the recessed shape in accordance with the outer face in the spherical shape of the steel ball and therefore, the steel ball can firmly be held in the click groove by guiding the steel ball in a direction of a center line of the recessed shape by the curved face of the recessed shape and even when external force is applied to the steel ball, detachment of the steel ball can be prevented, the steel ball can always be moved in the recessed shape and therefore, the movable piece is supported by pushing the movable piece to the side of the housing by the steel ball to thereby prevent detachment, sliding movement of the click groove relative to the steel ball can be carried out further smoothly, and operation feeling of the switch knob can be promoted by reducing friction resistance.
According to the invention of the fourth aspect, in addition to the effect of the invention according to any one of the first to third aspects, there are further provided the containing wall portion provided at the housing for surrounding the fixed contact, the slider supporting the elastic contact member and moved by operating to pivot the switch knob, and the slider cover attached to the containing wall portion attachably and detachably, forming the containing space for containing the slider and the movable piece between the slider cover and the containing wall portion and covering the slider movably and therefore, invasion of dust and dirt into the containing space is restrained by the containing wall portion and the slider cover, operation of the movable piece can firmly be carried out and contact and detachment of the fixed contact and the movable contact can be carried out further firmly. The fixed contact, the movable contact, the slider, the slider cover and the containing wall portion constitute a small-sized switch, the fixed contact and the containing wall portion are formed in the housing and therefore, a number of parts and a number of integrating steps can be reduced and cost can be reduced.